Swinging Bridge Reservoir Report

Last Updated: December 7, 2025

Swinging Bridge is a historic hydroelectric dam located in Sullivan, New York, along the picturesque Mongaup River.


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Summary

Built in 1930 by Chas. T. Main, Inc., this private structure stands at an impressive height of 135 feet and spans 975 feet in length. With a storage capacity of 37,000 acre-feet and a surface area of 1,000 acres, Swinging Bridge serves primarily for hydroelectric power generation, but also offers recreational opportunities for visitors to enjoy its scenic surroundings.

Maintained and regulated by the Federal Energy Regulatory Commission, Swinging Bridge poses a high hazard potential due to its size and location. Although its condition assessment is currently listed as "Not Available," the dam's emergency action plan was last revised in November 2020 to ensure preparedness for any unforeseen events. The dam's risk assessment categorizes it as high risk, emphasizing the importance of ongoing monitoring and risk management measures to safeguard both the structure and the surrounding environment.

For water resource and climate enthusiasts, Swinging Bridge presents a fascinating blend of history, engineering, and environmental impact. As a vital component of New York's energy infrastructure, this dam not only generates clean power but also contributes to the region's water management and recreational opportunities. With its rich heritage and significant role in the local ecosystem, Swinging Bridge remains a symbol of human ingenuity and the delicate balance between harnessing natural resources and preserving ecological integrity.

Year Completed

1930

Dam Length

975

Dam Height

135

River Or Stream

Mongaup River

Primary Dam Type

Other

Surface Area

1000

Drainage Area

118

Nid Storage

37000

Hazard Potential

High

Foundations

Soil

Nid Height

135
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.